Gamma ISP: Reference Manual

tree_cc

ANSI-C program: tree_cc.c

NAME
tree_cc - Uses the marked low correlation areas and residues (from the unwrapping flag file) and constructs a tree-like structure of branc cuts (walls). This branch cuts will not be crossed during the phase unwrapping. The walls are places that localize jumps of multiples of 2pi such as occur in regions of lay-over. The branch cuts are drawn been phase residues. These are points where the integral of phase around a path encircling the residue is a multiple of 2 pi.

SYNOPSIS
tree_cc <flagfile> <width> [mbl] [xmin] [xmax] [ymin] [ymax]

<flagfile>	phase unwrapping flag filename
<width>	number of samples/row
[mbl]	maximum branch length (default = 64)
[xmin]	offset to starting range pixel (default = 0)
[xmax]	offset last range pixel (default = width-1)
[ymin]	offset to starting azimuth row, relative to start (default = 0)
[ymax]	offset to last azimuth row, relative to start (default = nlines-1)

EXAMPLE
tree_cc 1352_1610.flag 2500 64

DESCRIPTION
tree_cc reads unwrapping flag file and uses the low correlation areas and the residues to construct a tree-like structure. The tree-like structure will not be crossed during the phase unwrapping to localize phase jumps to the regions defined by the cuts. Both low-correlation areas and residues are considered in the construction of the trees. The trees are written into the unwrapping flag file. For each pixel a single byte consisting of 8 bits is stored in the flag file. Each bit is used to denote a property of that particular pixel such as if it is a residue. The meaning of the individual bits is explained in the typedef_ISP.h file. The information contained in the unwrapping can be displayed with the programs disflag and rastree.

tree_cc generates a tree consisting of branch cuts with a minimum of extra cuts to create a sparse network or tree. It does this by a progressive search, connecting to any residues encountered in the search. The search distance from each residue is increased at each step thereby increasing the search area until the tree has no net charge (neutralized). When a tree is neutral, the program proceeds to find the next residue in the image that has not yet been connected and neutralized. Older, neutral trees in the flag file are used as pathways to find residues not yet incorporated in the trees of the flag file. Closed tree loops are avoided. by preventing cuts back to the origin of the tree. It differs from tree_gzw in that when an old discharged tree is encountered, this tree is searched out exhaustively to find all the tree members prior to continue with search. This search operation can take a significant amount of time for large trees. Another feature of this program is that regions of low correlation, when encountered are search immediately for a residues of opposite charge, irrespective of the current branch length.

SEE ALSO
typedef_ISP.h, tree_gzw, rastree, disflag.